His cat was said to be, according to quantum theory, both alive and dead simultaneously, until the box was opened. I am not sure this analogy does justice to the trickiness of this language! Maybe if it could morph into some other creature, immune to radiation or poison?

Until you open it, you'll never know what mysteries may lie inside the box (Schrödinger's society wasn't as obsessed with zombies and kitties as our own, so he clearly didn't account for the imaginable possibilities in that scenario) :)

You could also see that open-endedness as a more philosophical and humanist choice between glasses half full and glasses half empty - you decide what context to fill between the lines, and that like tell more about you than about the sentence itself. All in all, thinking about Portuguese is just as complicated as thinking in Portuguese - I'm glad you're finding that more of a good challenge than a dreadful bore :P

Revisiting this point, perhaps the alternatives would be indicated by excess stress on either Você or disse as it might be in English: (blame game) "YOU said .." and (credit where it is due) "You SAID .."